The present invention relates generally to optical scanning devices and, more specifically, to optical scanning devices for detecting the position of inherent defects marked with luminous paint on wooden planks or boards.
Lumber for use in the manufacture of furniture must be free from defects such as checks, loose knots, or planar skips. Because of the high cost of clear boards of matched lengths, it has become customary to process boards containing imperfections to remove the defects and use the boards so processed to make glued-up stock. In the past, such processing of defective boards has entailed manually severing the boards to cut out the imperfect parts. These operations have been highly labor intensive, and as a result of their reliance on human judgment to determine how and where boards should be cut, the lumber has not always been processed with maximum efficiency.
Consequently, computer controlled sawing systems have been developed to process lumber to be used in the manufacture of glued-up stock. These operations normally involve several processing steps including visually inspecting the lumber and marking any defects with luminous paint, scanning the boards to detect and record the relative positions of the marked defects, automatically computing the most efficient way to cut the boards, and then ripping and cross-cutting the boards to remove the defects. A critical step in the development of computerized sawing operations has been the design of effective scanning units. These units must operate to register the position of a board and photoelectronically scan across the surface of the board to detect any marked defects. The device must be provided with sufficient sensitivity of response, accuracy of detection, speed of operation, and electrical stability so that the unit may operate reliably in service.
Accordingly, it is an object of the present invention to provide a photoelectric scanning device capable of reliably detecting luminous marks on lumber boards.
It is another object of the present invention to provide a photoelectric scanning device of adequate sensitivity to detect small luminous marks, of sufficient locational capability to accurately determine the position of small marks, and of sufficient speed of operation to allow the device to rapidly accomplish its functions.
It is a further object of the present invention to provide a photoelectric scanning device of adequate stability of electrical operation and of competent output for interfacing with an electronic computational unit, and to provide a scanning device otherwise well suited to the purposes for which the same is intended.